This invention relates to a lid structure for an air bag system capable of preventing passengers in a vehicle from injuring themselves from inflation of an air bag during crashing of the vehicle.
Japanese Unexamined Utility Model Publication No. 3-16555 discloses a conventional lid structure through which an air bag inflates instantly when a vehicle is in a collision. In the structure of this prior art, an instrumental panel is provided with one opening which is formed on an assistant-seat side and through which the air bag can inflate outside of the panel. Normally, the opening is closed by a lid having an outer surface formed continuously with an outer surface of the instrumental panel. In the vicinity of a front part of a vehicle body, the lid is attached to the instrumental panel by mounting members. Provided inside of the opening of the panel is an air bag unit, which includes the air bag accommodated in a casing of resin and supported by a reinforcement to inflate in an emergency.
In operation, as soon as the vehicle crashes, the air bag begins to inflate. The air bag applies an inflating force on the lid such that the lid deforms and bends about portions of the lid which come into contact with the mounting members. Consequently, the opening is opened and then the air bag expands into the interior of the vehicle. In the lid structure as mentioned above, the opening must be formed to have a size enough to inflate the air bag smoothly and certainly.
However, in this arrangement, the lid for closing the openings is larger than the corresponding opening. Consequently, molding dimensions of the opening and the lid deviate from required dimensions. Consequently, such deviation exerts serious influences upon the conformity therebetween and the continuity between the surface of the lid and the surface of the instrumental panel. Thus, it causes the quality of the assembly to be lowered and causes the assembling operation to be difficult.